Nonreactive Scattering of N₂ from Layered Graphene Using Molecular Beam Experiments and Molecular Dynamics

Conventional gas surface interaction (GSI) models and molecular dynamics (MD) simulations have been compared with angular distributions and average translational energies for N₂ scattered from highly oriented pyrolytic graphite (HOPG) measured by angle and velocity resolved molecular beam scattering experiments. The translational energy and angular distributions of the scattered N₂ were obtained for incidence energies near 30 and 68 kJ mol^-1, incidence angles of 30°, 45°, and 70°, and a surface temperature of 677 K. The trajectories of scattered nitrogen molecules were found to fall into three main categories, i.e., single collision, multiple collisions with escape, and multiple collisions without escape. While the conventional GSI models did not match the translational energy and angular distributions obtained from the experiments, the results obtained from MD simulations were found to be in good agreement. The MD simulations also showed that the number of surface layers used to model the HOPG surface and the carbon-nitrogen Lennard-Jones potential are important in improving the agreement between the simulations and the experiments.